Circulation of liquid in chemical baths



15) 1940. w gag/ 5 CIR'CULATION OF LIQUID IN CHEMICAL BATIK;

Filed Oct. 26, 1938 Waiter @eyer :9 4% Mn! AQQM' Nov. 19, 1940 UNITED STATES PATENT OFFICE CIRCULATION F LIQISIID IN CHEMICAL Walter Geyer, Berlin, Germany Application October 26, 1938, Serial No. 237,148 In Germany October 26, 1937 3Claims.

veloping cinematograph films it has been proved ill ill

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that a good circulation of the developing liquid is absolutely necessary for avoiding the occurrence of striations and more particularly also of the effect of direction. developer in the developing apparatus is achieved mostly by pumping over'oi the liquid between the developing tank itself, through which the hire passes, and a mixing reservoir into which lresh reagent is added to that already used, in a proportion determined by the length of film under treatment. In using this arrangement, however, it is difllcult if not impossible to obtain a sumciently good circulation, owing to the reresistances of the inlet and outlet pipes with the 0 restricted cross sectional areas usually employed in practice. Moreover, it is very diflicul-t to obtain a suiilcient uniformity of the circulation.

According to the disposition in the tank of the inlet and outlet pipes leading to and from the 5 circulating pump. particularly in their relation one to the other, the flow of liquid tends to follow always certain more or less well defined paths: consequently there are certain zones in the tank, apart from the corners, where it is known for 0 static conditions to prevail, in which the liquid is hardly moved at all, being outside the influence of one of those defined paths of flow just mentioned. In particular, it has been found that only very seldom, and then accidentally, does the a circulation include the zones in the immediate vicinity of the film; despite the fact that this is most necessary, especially in the case of film developing, when the skin of liquid reagent actu-- ally contacting the photographic film and carried along with it needs to be replaced frequently.

in accordance with the present invention, the circulation oi the liquid is achieved by a vane wheel, or wheels, disposed within the film treating tank itself, conveniently in the immediate h vicinity of a partition which divides the tank into two compartments, and which is so disposed that both compartments are in communication with each other through at least two openings. The vane wheel can be rotated by the same U motor which drives the film itself.

The employment of the vane wheel for the circulation, as compared with the employment of pumps has the advantage of simplifying the design of the machine itself whilst the arrangement at the wheel within the tank enables one The circulation of theto omit the inlet and outlet pipes'for the liquid. The present invention enables comparatively rapid circulation of the liquid in thebath to be obtained by simple means and the homogeneity of the stream in all parts of the tank to be assured. The liquid stream, in this arrangement flows over the entire path or the film through the liquid in the immediate vicinity of the film, so that there occurs an effective replacement of the liquid actually in contact with the film. The

result of the aforesaid is a very great uniformity of the film treatment which, in the case of developing, avoids the undesirable efiect o1 direction.

One embodiment of the invention is shown in 1 opening through the partition 2, in such a way I that when rotated it causes a flow of liquid from one of the compartments 3, l to'the other along the bottom of the tank. The vane wheel can be driven, for example, by means of a pulley 6 which may be arranged within or externally oi the tank. In the illustrated arrangement, strips of film i are carried down into both compartments; but instead of this arrangement one compartment, for example compartment 3, may not constitute a film bath, but for example may accommodate the developer feed and be equipped with a device for regulation of the temperature. Further, a plurality of such tank aggregates may be employed for one and the same bath or for a plurality of baths in sequence.

1 claim:

1. An arrangement for the circulation of photographic baths in a. film developing apparatus comprising in combination, a dipping tank adapted to contain a liquid, a flat internal partition dividing the tank into at least two compartments which compartments intercommunicate around the partition, means for supporting anddriving film in a path parallel to said partition, and an axially elongated vane wheel mounted within the tank. to cause the circulation of liquid within the compartmentsin a. direction generally parallel to said partition for the length thereof, the axis of said vane wheel being parallel u to an edge of said partition.

2. An arrangement for the circulation or photographic baths in a fllm developing apparatus comprising in combination, a dipping tank adapted to contain liquid. a flat, vertical internal partition dividing the tank into at least two compartments, which compartments intercommunicate above and below the partition, means for supporting and driving film in a path parallel to said partition, and an axially elongated vane wheel mounted within the tank adjacent a point of intercommunication of said compartments for causing the circulation of liquid within the com partments in a direction generally parallel to said partition for the length thereof, the axis of said vane wheel being parallel to an edge of said partition.

3. An arrangement for the circulation 01' photographic baths in a film developing apparatus comprising in combination, a dipp tank adapted to contain liquid, a flat internal partition dividing the tank into at least two compartments, which compartments intercommunicate above and below the partition, means for supporting and driving film in a path parallel to said partition, and a vane wheel mounted across the tank for causing the circulation of liquid within the compartments in a direction generally parallel to said partition for the length thereof, said vane wheel being of a length substantially co-extensive to the width oi the tank.

WALTER GEYER. 

